More than half of the consumers who used Scan & Go in the initial part of the pilot returned and used it again, reports Wal-Mart, No. 4 in the Internet Retailer Top 500 Guide.

“We are pleased with the engagement,” Wal-Mart’s Gibu Thomas, senior vice president of mobile and digital, tells Internet Retailer. “We didn’t have any specific numbers we were targeting. It was more test and learn. What do customers like, where do we need to do better? This has been a behavioral change for our customers and we’re pleased the people who are using it are engaging with it as positively as we have seen.”

Wal-Mart has learned a lot from the pilot and customer research so far—some obvious lessons and some surprising. An obvious lesson, Thomas says, has been that customers like to use Scan & Go as a budgeting tool—customers can see what their total bill is as they shop. One lesson that has been a pleasant surprise, as Thomas describes it, is that Scan & Go customers like to bag their own groceries and merchandise.

“People have a method to how they unpack their groceries when they get home,” Thomas says. “Some things go in the refrigerator, some things go in the pantry, some things go in the bathroom. Customers like being able to bag items in the way they would unpack them. This is not something we anticipated. And it’s these kinds of things we’re really looking at, what are the core experiences people are engaging and what are opportunities for us to make them better?”

In addition to expanding the Scan & Go program, Wal-Mart has added an electronic receipt option. Customers can opt to store an exact replica of the physical receipt in a special section of the iPhone app.

“Overall our customers are becoming more digital; that means their shopping experience is becoming more digital,” Thomas says. “With an electronic receipt customers can see purchases and plan their next visit, they can easily find their receipt if they return an item—the electronic receipt helps customers interact with us better.”

Thomas wouldn’t say whether smartphone-carrying customers are more valuable to Wal-Mart than customers without smartphones, but he did say more than half of Wal-Mart’s customers carry smartphones and that customers who shop in more than one sales channel are more valuable.

“A multichannel customer is more valuable to Wal-Mart—they shop more frequently with us and buy more,” he says. “Our strategy is around seamless access to Wal-Mart, and mobile is a big piece of that, as customers have a smartphone in-store and a smartphone and a tablet at home. So when you are in-store we can give you Scan & Go, and at the same time you are just one tap away from access to our entire online assortment. We’re being more customer-centric by giving our customers more choices in terms of shopping the way they want in the channel they want.”

Thomas expects to expand the Scan & Go pilot even further, though he does not have a timetable. He adds that a version of Scan & Go soon will be available in the retailer’s Android app. Wal-Mart is promoting the mobile checkout service on its e-commerce site at Walmart.com/ScanAndGo.